1. Field of the Invention
The present invention relates to a photographic apparatus and method for the processing of image-wise exposed photographic silver halide emulsion layer elements, and in particular to such apparatus and method for the convenient processing of photographic film sheets with micro-images, such as COM (computer output microfilm) fiches, that are produced by so-called low-end users, or microfilm recorded in a microfilm camera.
Micro-images are commonly photographically processed according to one of the following two processes.
The first process is a "dry processing" silver halide system, wherein an image is generated after exposure and thermal development of a light-sensitive layer containing minor amounts of light-sensitive silver halide, an organic silver soap and a reducer. This system has the important advantage of dry processing (no liquids), but it has been shown that the storage conditions of the film are critical, and that the processing is temperature-dependent, resulting in variations in the gradation and the maximum density of the film. A further disadvantage is the low archivability of these images.
The second process is the classic silver halide process that offers very satisfactory images, but that is hampered by the use of a developer liquid that requires controlled regeneration in view of aerial oxidation, and that thereby is less convenient, in particular for the low-end user who makes approximately 5 to 50 microfiches per week.
2. Description of the Related Art.
It is known in other domains of photographic reproduction, for instance for graphic line and screen-work, to use light-sensitive silver halide emulsion material that incorporates its own developing agents which become active by contact with an alkaline activation solution. In this process, there is no premature oxidation of the developing agents by exposure of the developing liquid to the air as in conventional silver-halide photography, whereby the processing liquid regeneration becomes more simply.
The convenience of photographic processing is further improved if the processing solutions are supplied to the different processing stations by means of bottles of a reduced content, e.g. 1 1 bottles, that are placed in inverted position on the apparatus and the content of which is supplied to processing stations with a chicken-feed level control system.
Activation-type photographic processing apparatus of this kind can be left in stand-by condition for periods ranging from days to weeks, and yet they are capable of producing good processing results after a few seconds of running-in.
In spite of the mentioned advantages, the described inverted bottle-type processing apparatus still show some disadvantages which make their use less convenient than it could be.
A first disadvantage is formed by a particular valve that is required for the bottles with processing liquid, and that becomes only opened at the moment the inverted bottle reaches its operative position in the fitting of the apparatus.
Another point is that a bottle may run dry. This is not a serious problem in the processing of large-format images, e.g. an A4 format sheet, since the discarding of one unsatisfactory processed image usually does not mean a great loss. However, in the case of COM recordings, one film fiche may contain up to 120 different images, and the loss of one film sheet in consequence means that all these different recordings must be done over.
If an empty bottle is replaced by a fresh one, and the other bottle(s) is (are) not replaced at that moment, it may take only a short time before another bottle runs dry and leads on its turn to the immobilisation of the apparatus.
Furthermore, the holder for rinsing water must be overproportionally large, since the rinsing water becomes loaded with substances that were dissolved and leached out by the fixing of the developed photographic silver halide element. The concentration of such substances in the rinsing liquid may not surpass a given level otherwise the rinsing becomes unsufficient. The latter problem may be overcome by the connection of the apparatus to tap water supply, but this measure considerably reduces the convenience of use of the apparatus.
Finally, the different processing stations must be provided with liquid discharge means in order to empty such stations prior to their removal from the apparatus for cleaning purposes or servicing. In the case of processing sections in the form of shallow trays that are not emptied while in the apparatus, the operator must carefully remove such tray from the apparatus and bring it to a sink for pouring away the liquid.
It is an object of the present invention to provide an improved photographic processing apparatus for the wet processing of exposed photographic silver halide emulsion layer elements e.g. sheets, the use of which, and in particular the use of the processing solutions involved in its operation, is more convenient than in the known apparatus.
It is further an object of the present invention to combine convenience of processing with an economical use of processing ingredients and wash water without detrimental effects on the archival properties of the final image.
A still further object of the invention is the provision of an apparatus of the type referred to, which is compact and can readily be used in an office.